The present invention relates to the field of acoustic duct silencers, and more particularly, to modular elbow silencers.
The use of high-performance Heating Ventilation and Air Conditioning (HVAC) systems has resulted in unacceptably high noise levels in buildings. Obtrusively loud noise from ducts used in an HVAC system can effect the overall environment in a building by transmitting unwanted sound throughout the building. Additionally, air flowing through abrupt changes in the cross-sectional dimensions of a duct can also produce sound. Accordingly, there has been a longstanding problem with the amount of sound transmitted through the ducts of an HVAC system.
Various attempts have been made to minimize the sound propagation in straight air ducts. One such attempt provides a sound attenuating silencer lined on the inside of the straight air duct.
Sound attenuating silencers have also been used in elbow ducts to reduce noise propagation. Elbow silencers currently used in the industry are modified standard linear silencers which are typically bent at an angle of approximately ninety degrees.
FIG. 1A illustrates a conventional one-piece elbow silencer 110 currently used in industry which typically includes a casing having a baffle 120 which defines two flow channels or paths 130 and 140. With this construction, each air or sound flow channel or path 130 and 140 defined by the baffle 120 has a different length, making pressure loss, self generated noise and sound attenuation unpredictable and unreliable.
Another conventional arrangement of elbow silencers is illustrated in FIG. 1B. The arrangement shown in FIG. 1B uses two elbow silencers 150 and 160 which are positioned in a nested relationship. The air or sound flow channels 130 and 140 of the two elbow silencers 150 and 160 are similar to the flow channels of the elbow silencer 120 shown in FIG. 1A because each defines a different length which, again, makes pressure loss, self generated noise and sound attenuation unpredictable and unreliable.
Turning vanes have also been used in an attempt to minimize the sound propagation in existing elbow air ducts. Turning vanes are baffles that are inserted into a single duct which define flow channels for the air flow. However, turning vanes are impractical because they require insertion of multiple baffles into an existing single duct. Turning vanes are also inconsiderate of space constraints and it is time consuming and expensive to insert the baffles into a single duct.
The present invention provides a modular acoustic elbow silencer which is configured to attenuate sound and is capable of being nested with another, complementary elbow silencer. According to one embodiment, an elbow silencer for attenuating noise associated with a fluid medium passing through said elbow silencer comprises a casing and a baffle. The casing includes sides that define an inlet end and an outlet end. The baffle is disposed within the casing and defines a flow channel through which the fluid medium passes. The elbow silencer is capable of being nested with a complementary elbow silencer having substantially the same flow channel.